To discriminate between these possibilities, we analyzed the phylogenetic relationships of 20 great ape Hepatocystis sequences (i.e., three Kanyawara-derived sequences and 17 unpublished sequences amplified fortuitously during previous molecular epidemiological studies of ape malaria parasites1,2,7) relative to 56 previously published Hepatocystis cytB sequences (Supplementary Data 2) isolated from a wide range of hosts, including African and Asian monkeys, bats, and other mammals (Fig. 3). The gene discussed is MT-CYB; the disease is malaria.